JPH1094779A - Dehydrating method of organic waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To economically dehydrate organic waste as a pre-treatment of fermentation by heating the organic waste by a heat treatment including no drying process to dissociate a combined water in a cell or to weaken the bond and after that mechanically dehydrating the organic waste. SOLUTION: A raw material 1, if necessary which is cutted or in which water is added, is housed in a heat treating vessel 2 with a cap 2a. The heat treating vessel 2 has a heater 3 for heating the inside. The raw material 1 housed in the heat treating vessel 2 is heated at an adequate temp. after the cap 2a is closed. As a result, the raw material 1 is heated in a state without drying to dissociate the combined water or to weaken the bond. The raw material 1a treated by heating is transported by a conveyer 4, housed in a dehydrator 5 of a mechanical dehydrating means and dehydrated. Since the combined water is dissociated or is weakened in the bond by the way, the cell is effectively dehydrated with the combined water and the fermentation efficiency in a fermenter 8 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to organic waste such as garbage discharged from kitchens of ordinary households, or plant-based or animal-based agricultural waste such as tangerines, cabbage, and onions.
The present invention relates to a dehydration treatment method which is performed as a pretreatment when fermenting for composting, feed conversion, volume reduction, and the like.

[0002]

2. Description of the Related Art In recent years, it has become widespread that organic waste is crushed, aerobic fermented, and effectively used as compost, and is effectively used as feed or reduced in volume for waste disposal. Attempts have been made to make it easier. However, organic wastes containing a large amount of plant matter usually have a very high water content of 80 to 90%, and thus have a disadvantage that they have poor air permeability and are difficult to undergo aerobic fermentation. For this reason, conventionally, prior to the fermentation treatment, the water content of the organic waste is adjusted to an appropriate amount so as to facilitate aerobic fermentation. Examples of the method for adjusting the water content include a method in which organic waste is dried in advance by a heat source incorporated in the fermenter, a method in which hot air is blown into the fermenter to evaporate water, sawdust having a low moisture content in organic waste, and firs. A method of mixing husks and the like, a method of returning and mixing treated compost (with a low moisture content), and a method of using a water conditioner to adjust the water content, and a method of mechanically adding organic waste. A mechanical dehydration method or the like of adjusting water content by pressure dehydration, vacuum dehydration, centrifugal dehydration, or the like is employed.

[0003]

However, all of the above-mentioned conventional methods for adjusting moisture have significant disadvantages.
For example, when drying with a heat source or hot air, 10% of organic waste
A great deal of energy is required to heat to 0 ° C. and to provide latent heat of vaporization of water, and the cost of drying the water content of organic waste to an appropriate amount suitable for fermentation is very high. Problem. Further, in the case of using a water adjusting material, an extremely large amount of the water adjusting material is required in order to reduce the water content of 80 to 90% to an appropriate water content, and it may be difficult to obtain the water adjusting material. In addition, there is a problem that not only the running cost is increased but also the volume reduction rate is greatly reduced in the process for volume reduction. There is also a problem that the capacity of the fermenter is doubled and the construction cost and operation cost of the processing equipment are increased. Furthermore, depending on the water content of the organic waste, it is necessary to return a large amount of compost obtained by the fermentation process and use it as a water conditioning material. is there.

Further, in a mechanical dehydration method using means such as pressure dehydration, vacuum dehydration, and centrifugal dehydration, water adhering to the surface of organic waste can be relatively easily dehydrated.
However, the moisture adhering to the surface of the organic waste is usually low and most of the water is present in the form of intracellular bound water inside the waste. Therefore, if the organic waste is cut and mechanical dewatering of bound water is immediately attempted, a very large load must be applied to each cut piece, which must be crushed to the cell level to dissociate the bound water. Must. However, in this state, the organic waste becomes a muddy material that is difficult to filter, and the dewatering efficiency is greatly reduced.
With the mechanical dehydration method, it is difficult to effectively remove intracellular bound water to perform dehydration.

[0005] The applicant of the present invention has proposed, as an alternative to the above-mentioned water regulation method, a method in which organic waste is subjected to a passerative anaerobic fermentation treatment and then mechanically dewatered (Japanese Patent Publication No. Sho 64).
-1438). According to this method, the intracellular bound water of the organic waste is dissociated by the facultative anaerobic fermentation treatment, and the dewatering can be performed effectively including the intracellular bound water in the subsequent mechanical dehydration. However, in this method, there is a problem that the facultative anaerobic fermentation treatment takes a long time, and furthermore, in order to secure a necessary amount of dehydrated organic waste within a predetermined period, a large size is required. However, there is a problem that an apparatus for anaerobic fermentation is required. There is also a problem that a strong putrefaction odor is generated during anaerobic fermentation.

The present invention has been made in view of the above circumstances, and solves the above-mentioned conventional drawbacks. As a pretreatment for fermentation, an organic waste capable of economically and effectively dehydrating organic waste is provided. It is an object of the present invention to provide a method for dehydrating a municipal waste.

[0007]

Means for Solving the Problems In order to solve the above problems, the first invention of the organic waste dewatering method of the present invention is to heat the organic waste by a heat treatment not including a drying treatment. And dissociating or weakening the intracellular bound water of the organic waste, and then mechanically dehydrating the organic waste. According to a second aspect of the present invention, in the first aspect, water is added to the organic waste prior to the heat treatment.

According to the present invention, organic waste is subjected to dehydration. Examples of the organic waste include kitchen garbage generated from kitchens such as general household kitchens, lunch centers, central kitchens, and hospitals. However, the field of the present invention is particularly limited in the present invention. Not something. In addition, organic wastes include plant-based materials such as vegetables, fruits, and flowers,
There are animal species such as fish and meat, but these are not particularly limited in the present invention. However, as a target, garbage, which has a high water content and greatly affects fermentation efficiency depending on the dehydration treatment, is preferable.

The above-mentioned organic wastes, that is, the cells constituting these organisms, are composed of cell membranes, nuclei, cytoplasms and enzymes, and the protoplasm which is the basic substance of the cells is composed of water, proteins, lipids and sugars. Quality, ash etc.
Water accounts for 60-99% of the protoplasm. Therefore, usually, the water content of the organism is reduced only slightly by removing the moisture attached to the surface of the organism such as garbage. For this reason, in order to effectively dehydrate, it is necessary to destroy even the cells of the organism and remove bound water to the surface of the organism.

According to the present invention, the organic waste is heated by a heat treatment which does not include a drying treatment prior to the mechanical dehydration to effectively remove intracellular bound water. Is unnecessary and no off-flavor is generated. In the above heat treatment, it is possible to heat the organic waste as it is. However, in order to increase the efficiency of the heat treatment, the organic waste is removed by 5 to 20 m before the heat treatment.
It is desirable to cut it into a size of m. Cutting can be performed by a conventional method using a crusher or the like. The reason that the above size is desirable is that if the size is larger than 20 mm, the bound water inside the cut piece is less likely to appear on the surface,
On the other hand, if the size is smaller than 5 mm, the bound water tends to come out to the surface, but on the other hand, since the size of the cut pieces is small, the state becomes close to a hardly filterable mud during mechanical dewatering, and the dewatering efficiency is reduced. It is because it falls. In addition, as long as the organic waste has the above-mentioned size in a raw material state, cutting work is not particularly required. In addition, not including the drying treatment means that the purpose is not to actively dry (reduce the water content). For example, evaporation of organic waste occurs spontaneously as the temperature is increased by heating. The heat treatment which does not include the drying treatment according to the present invention can be said to be a treatment in which the water content is slightly reduced. However, a heat treatment of boiling all the time except at the beginning of heating can be said to be aggressive drying, and is excluded from the present invention.

It is also possible to add water to the organic waste before the heat treatment, and the addition of an appropriate amount of water makes it easier to remove bound water as described later. this is,
This is for facilitating the transfer of heat through water or steam to a place where heat is hardly transmitted, thereby shortening the processing time. If the water content is too small, the effect is small, and if the water content is too large, additional heating energy is required. From these viewpoints, the amount of water added is 100 g of organic waste,
It is desirable to add 20 to 60 cc.

In the heat treatment, the cells themselves are well heated by heating not including the drying treatment, and the cell walls (plant only),
Proteins and the like in the cytoplasm are denatured, and the cell shape maintenance function is lost. An action such as influx of water or expansion of intracellular substances is applied thereto, and the cells are destroyed to dissociate the bound water, and the water inside flows out. Even if it is not broken, the bond is weakened, and it is easily broken even by a small load, and moisture comes out to the outside.

It is desirable that the above-mentioned heating does not involve drying so that the cells themselves are well heated, and furthermore, it is desirable to take measures for preventing or suppressing the drying. This method includes heating the organic waste in a container having a small opening or no opening. In addition, when the drying of the organic waste proceeds in the heating, there is a problem that energy loss is large and the dried waste adheres to the wall surface of the heating container. In the heating, it is desirable to heat the organic waste to 40 to less than 100 ° C. This is because if the temperature is lower than 40 ° C., the loss of the morphological maintenance of the cells is not sufficiently achieved, whereas if the temperature is higher than 100 ° C., the effect is only saturated and the required heating energy is increased by boiling. desirable. It should be noted that the upper limit is more preferably set to 80 ° C. or lower, because of the same reason and some of the organic substances are burnt at around 100 ° C. In the above heat treatment, heating can be performed by use of an appropriate heat source or irradiation of microwaves,
This can be used in combination. When heating,
The organic waste may be agitated during heating so that the entire organic waste is evenly heated.

After the heat treatment, mechanical dehydration is performed.
Examples of the mechanical dehydration method include pressure dehydration, vacuum dehydration, centrifugal dehydration, and the like, but are not limited thereto, and an appropriately selected mechanical dehydration unit can be selected. By the above-mentioned series of steps, the organic waste is
Dehydration is performed efficiently, including intracellular bound water. In addition, the energy required for the treatment can be lowered significantly in some cases, because the temperature at the time of heating can be lowered.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below. Raw material 1 with cutting and addition of water as required
Is housed in a heat treatment tank 2 with a lid 2a. The heat treatment tank 2 has a heater 3 for heating the inside. After the raw material 1 is accommodated in the heat treatment tank 2, the lid 2a is closed, and the raw material 1 is heated to an appropriate temperature. As a result, the raw material 1
The cells are heated while drying is prevented, and the cells dissociate or dissociate the bound water.

The heat-treated raw material 1a is transferred by a conveyor 4 and stored in a dehydrator 5 which is a mechanical dehydrator. In the dehydrator 5, dehydration is performed by a conventional method. At this time, the raw material 1a is effectively dehydrated, including the intracellular bound water, since the intracellular bound water is dissociated or weakened as described above. As described above, the raw material 1b dehydrated to a water content suitable for fermentation is sequentially fed to the fermenter 8 having the scoop type stirrer 7 by the conveyor 6.
In the fermenter 8, the fermentation is efficiently performed as a raw material 1 c for fermentation, and is converted into compost or feed, or the fermentation rate is increased to reduce the volume, if desired.

[0017]

【Example】

(Example 1) Organic waste: (1) Cabbage (crushed 5 mm) (2) Cabbage + carrot + ground meat (crushed 5 mm) (60 g) (50 g) (40 g) Any one of the above organic wastes Raw material 10 consisting of 2
The beaker 12 was placed in an oil bath 13 and the opening of the beaker 12 was covered with an aluminum foil 14 and capped. These were subjected to a heat treatment of heating at 80 ° C. for 60 minutes, immediately cooled, and then subjected to centrifugal dehydration (mechanical dehydration) at 5000 rpm for 10 minutes using a centrifuge. The water content of the raw material 10 before and after the dehydration treatment was measured and is shown in Table 1. In addition, as a comparative object, one subjected to mechanical dehydration without performing heat treatment, and one subjected to spray anaerobic treatment at 30 ° C. for three days after spraying fermentation extraction water, and then mechanically dewatered. These were prepared, and the water content before and after the treatment was measured.

[0018]

[Table 1]

(Example 2) Organic waste: cabbage (crushed 5 mm) The raw material 20 composed of the above organic waste and 25 cc of water 21 were mixed for 200 m.
The beaker 22 was placed in an oil bath 23, and the opening of the beaker 22 was covered with aluminum foil 24 and capped. This is changed to 80 as in the first embodiment.
℃, heat treatment for 60 minutes, immediately after cooling, 5000
After centrifugal dehydration at 10 rpm for 10 minutes, the water content before and after the treatment was measured. In addition, as a comparison object, a mechanically dehydrated one without performing a heat treatment in the same manner as above, and a fermentation-treated extracted water sprayed thereon, followed by a facultative anaerobic treatment at 30 ° C. for three days, The dehydrated one was prepared, and the water content before and after the treatment was measured.

[0020]

[Table 2]

As is evident from the above examples, the dehydration method of the present invention has a clearly superior dehydration performance as compared with other methods. In addition, there is an advantage that the heating temperature is low and the required heating energy is small.

[0022]

As described above, according to the method for dehydrating organic waste of the present invention, the organic waste is heated by a heat treatment which does not include a drying treatment, and the cells of the organic waste are heated. Since the organic waste is mechanically dewatered after dissociating the internal bound water or weakening the bond, the organic waste can be effectively dehydrated without requiring large heating energy. As a result, the organic waste can be easily dewatered to the water content required for aerobic fermentation, and the fermentation efficiency can be improved.

Further, if water is added to the organic waste prior to the heat treatment, in addition to the above-mentioned effects, heat is easily transmitted through water or steam to a place where heat is hardly transmitted (particularly the center).
This has the effect of reducing the processing time.

[Brief description of the drawings]

FIG. 1 is a front view of a dehydration processing apparatus for carrying out a method of the present invention.

FIG. 2 is a perspective view of a test apparatus used in the example.

FIG. 3 is a perspective view of a test apparatus used in another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw material 1a Raw material 1b Raw material 1c Raw material 2 Heat treatment tank 3 Heater 4 Conveyor 5 Dehydrator 6 Conveyor 7 Scoop stirrer 8 Fermenter

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C05F 17/00 C05F 17/00

Claims (2)

[Claims] 1. An organic waste is heated by a heat treatment not including a drying treatment to dissociate or weaken intracellular bound water of the organic waste and then mechanically remove the organic waste. For dehydration of organic waste characterized by selective dehydration 2. The method for dehydrating organic waste according to claim 1, wherein water is added to the organic waste prior to the heat treatment.